Regulation of gene expression in Corynebacterium glutamicum represents an important issue since this Gram-positive bacterium is a notable industrial amino acid producer. Transcription initiation, beginning by binding of RNA polymerase to the promoter DNA sequence, is one of the main points at which bacterial gene expression is regulated. More than 50 transcriptional promoters have so far been experimentally localized in C. glutamicum. Most of them are assumed to be promoters of vegetative genes recognized by the main sigma factor. Although transcription initiation rate defined by many of these promoters may be affected by transcription factors, which activate or repress their function, the promoter regions share common sequence features, which may be generalized in a consensus sequence. In the consensus C. glutamicum promoter, the prominent feature is a conserved extended -10 region tgngnTA(c/t)aaTgg, while the -35 region is much less conserved. Some commonly utilized heterologous promoters were shown to drive strong gene expression in C. glutamicum. Conversely, some C. glutamicum promoters were found to function in Escherichia coli and in other bacteria. These observations suggest that C. glutamicum promoters functionally conform with the common bacterial promoter scheme, although they differ in some sequence structures.

Institute of Microbiology Academy of Sciences of the Czech Republic Vídenská 1083 CZ 14220 Prague 4 Czech Republic

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Corynebacterium glutamicum promoters: a practical approach

General and molecular microbiology and microbial genetics in the IM CAS